Off Topic (Space Related) - Downlinks

[Cosha]

So, i cant find a great deal on the interweb for a question i have, and i thought a few of you experts could shed some light...

I just read an artical that got my brain hurting a little!

Voyager 1, is over 10 billion miles away from Earth, it was launched in 1977 and still to date is sending information and images back from that far away! Mind boggles...!

How does this information get sent back? It seems a great deal away for a singal to reach home! :confused:

I know its not photography related, just intrest to do with starts and space!

[Bernoulli]

It uses a little radio and big antennas:

http://www.howstuffworks.com/question431.htm

Data rates are pretty low by internet standars, only about 100 kb/sec. That's lousy even for dial-up.

It's about three times further away than Pluto right now, and the signal takes about 16 hours to go one way, at the speed of light no less!

[Cosha]

Now why could i not find that :confused:

Intresting how it says it send to earth only using 32-watts on 8Ghz, but 'Then when the earth antenna transmits back to the spacecraft, it uses extremely high power (tens of thousands of watts) to make sure the spacecraft gets the message'

must takes weeks if not months to send a small image back :D

[gjl711]

Here is another nice link. Click on the "need to know " links for more info.
http://voyager.jpl.nasa.gov/mission/

[archer1960]

Extremely high-gain transmitting antennas and even bigger receiving antennas on the ground (100m or so across, IIRC). I don't think it's sending any pictures back these days, just data from its other instruments. Not much to see out there...

[Cosha]

Thanks guys! I'm reading away like crazy!

[altitude604]

Now why could i not find that :confused:

Intresting how it says it send to earth only using 32-watts on 8Ghz, but 'Then when the earth antenna transmits back to the spacecraft, it uses extremely high power (tens of thousands of watts) to make sure the spacecraft gets the message'

must takes weeks if not months to send a small image back :D

difference is that here on Earth, we have to contend with breaking through the Ionosphere to get the signal out so we need MOAR POWERRRRR. ;)

whereas previously mentioned, to receive they use large array antennae to pick out what's left of the signal after it's been attenuated by its long journey.

generally with excessively long distance communication (ie VLF, ELF used by Submarines) the data rate is really low (ELF is something like 300 baud iirc) to maintain the integrity of the information. it's like sending morse code at 5wpm so you know that the guy at the other end can copy it all down or fill in the blanks easy if he misses a character.

/Ham Radio Brain Speak

[Cosha]

Ah thanks for that! I build small uavs as my other hobby, I'm joint a ham club next year to learn more about radio waves etc...

I guess if I put it to what I relate to is that a 10mw video signal being sent by a 3dbi omni antenna and received by the same is not an efficient way Of doing it, yet use a 20dbi patch antenna on the reciever with a tracker yeilds a better result!

I guess I'm just taken back on how bloody far that signal is being picked up from!!

Sorry all of this is off topic in a photography forum just I knew you guys would help me more!

[mtbdudex]

heres some photography with V'ger in it........:)
http://www.beyondspock.de/Bilder/film/ST_I_VGer_1_big.jpg

[Cosha]

Love it!

[altitude604]

Ah thanks for that! I build small uavs as my other hobby, I'm joint a ham club next year to learn more about radio waves etc...

I guess if I put it to what I relate to is that a 10mw video signal being sent by a 3dbi omni antenna and received by the same is not an efficient way Of doing it, yet use a 20dbi patch antenna on the reciever with a tracker yeilds a better result!

I guess I'm just taken back on how bloody far that signal is being picked up from!!

Sorry all of this is off topic in a photography forum just I knew you guys would help me more!

It's really neat stuff! I got my Ham License back in 1994 with the assistance of my Father who is ex-Military Signals as well. lol

Moonbounce VHF communication is another cool mode of radio transmission that's worth a read on. They have contests every year where they use yagis and other directional antennae to bounce their signals off the Moon to other stations on Earth.

It's weird being one of the "younger" people to still have a functional knowledge of Morse Code. :lol: